ISA Server 2004 UNLEASHED [Electronic resources]

Configuring Add-ins

One of the biggest advantages to ISA Server 2004 is its ability to have its base application-filtering engine easily extended with third-party add-in functionality. This makes ISA a strong candidate for software to provide advanced web filtering, anti-virus applications, intrusion detection filters, and additional VPN capabilities.Part III of this book, "Securing Servers and Services with ISA Server 2004."

Exploring Application Filters

Application filters in ISA were specifically created to examine the traffic being passed through the server and make sure that it is not simply a piggy-backed exploit or attack. Each application filter contains language specific to the protocol it is filtering, so it can identify and block traffic that does not comply with the proper use of the protocol. The following application filters are configured by default in ISA Server 2004:

• DNS filter

• FTP Access filter

• H.323 filter

• MMS filter

• PNM filter

• POP Intrusion Detection filter

• PPTP filter

• RPC filter

• RTSP filter

• SMTP filter

• SOCKS V4 filter

• Web Proxy filter

Examining Web Filters

In addition to the default application filters available with ISA Server 2004, a series of web filters is also installed that extends the capability of ISA to scan incoming web (HTTP) packets. These web filters, shown in Figure 3.35, allow for advanced HTTP filtering capabilities, such as the capability to secure Outlook Web Access (OWA) traffic, or the capability to perform Link Translation.